Treatment Of Pesticide Wastewater By Combining Microbial Fuel Cell With Aluminum Sludge-based Constructed Wetland

Energy scarcity and environmental pollution are currently global two majorchallenges,especially agricultural runoff pollution.The residual of pesticides in agricultural activities,with the rainwater infiltration to the underground aquifers has caused groundwater pollution.In the traditional sewage treatment of activated sludge process,it isthrough the use of aeration and secondary precipitation to treat sewage.This method consumes large amount of electricity and produces massive excess sludge,increasing the difficulty of follow-up treatment.Artificial wetland technology is the use of filler,microbial,plant three synergies,through the physical,chemical,biological interaction to treat the sewage.The basic principle is like the biofilm method.Artificial wetlands are used in the treatment of domestic sewage,industrial wastewater,rainwater runoff,agricultural runoff pollution etc.,which is an environment-friendly sewage treatment technology.In recent years,the development of microbial fuel cell(MFC)technology has shown the promising in water pollution control.MFC technology is a kind of evolution in the development of fuel cell technology.It mainly relies on the catalytic effect of electricity microbial.The decomposition of organic matter will release to the micro-organisms in vitro,and then use the electronic collection device,constitute the current circuit,thus producing electricity.A Horizontal SubSurface Flow Constructed Wetlands with partitions has been used in this study.The wetland substrate is made of dehydarted aluminum sludge from a water supply plant.Two classes of MFC systems are provided at different locations between the partitions in which the first class of MFC uses glass wool as a separation material while the secord class of MFC has no separator.The experimental water came from manual modulation and the duration of this study was lasted for 255 days in 4 stages.The 4th stage includes 3 specific sub-stagesfor exploring the influences of contaminants removal and MFC electric production performance caused by organic matter.The last stage mainly studied the removal efficiency of Triazophos pesticide by changing the concentration oftriazophos in water and observing the removal effect of pollutant and the electric production performance of MFC system.Main conclusions are as follows.Aluminum sludge is feasible as a filler for constructed wetlands.Under different loading conditions.The overall removal efficiency of COD,NH4+-N and TP was 90±2%,47.89±2.65% and 96%,respectively.The aluminum sludge in the water plant contains a lot of Al3+.Al3+ and PO43-can form a precipitate.The removal loading of phosphorus from wetland in this experiment is as high as 1.2 g / m2·d.The removal of triazophos from activated carbon and aluminum sludge in this experimental is effective,and the presence of triazophos has not been detected in effluent.The root zone of wetland plants also has a certain effect on the removal of triazophos.In the early stages,increasing the COD concentration can provide more carbon sources for a microorganism that produces electricity.However,when the COD concentration continues to increase,it will cause heterotrophic bacteria and a microorganism that produces electricity competition for carbon sources.The maximum voltage of the MFC system with the diaphragm is 1085.3±117.3mV.The maximum voltage of the MFC system with no diaphragm is 983.9±102.1mV.MFC's internal resistance is not only related to the electrode spacing,but also with the presence or absence of split material.The partitioning material prevents the oxygen in the cathode from entering the anode region while also affecting the transmission of the anode protons.The test with the diaphragm MFC internal resistance is 798.9?,The other MFC internal resistance is 177.1?.The former is 4.5 times thanthe latter.In the initial stage of the addition of triazophos,the voltage of the two-stage MFC system did not change greatly,which indicated that the microbes produced some resistance to triazophos pesticides.Compared with ammonia,nitrogen removal effect is declining,indicating that nitrifying bacteria are more sensitive to triazophos pesticides.